US2336198A - Apparatus for seismic prospecting - Google Patents

Description

Deb. 7, 1943." c. chs'roTz 2,336,198

- APPARATUS FORHSEISMIYC PROSPECI'ING Filed April 19, 1940 i/wmrok, Cmmzs C. Srorz.

' Figure 3 is a top plan view I Figure 4 is a transverse, sectionalviewof the atente Dec. 7, E43

are

that, 0. site, s e rear, cam. Application April 119, 19%, ficrlal No. 330,559

g 3 Claims. $11. iii-352) This invention relates to an apparatus for seismic prospecting, and particularly 'toan apparatus which visually records the sound wave-reflected from various sub-surface strata and bodies.

.Sincethe amplitude of the recording needle or stylus is inpropor'tion to the intensity of the earths vibration, an olgiect or my invention, therefore, is to provide a novel means of controlling the amplifier and the throwof the recording stylus or-needle. This'control or. controls remains constant when once adjusted.

Another object is toprovide'a novel cut-out [from being overenergized' or paralyzed by the ini- ,tial shock of a surface or sub-surface explosion or impact.

A featureof my invention resides in the definite indicationon a visual chart oivarious subsdr face strata, as well as the depth and thickness of non-vibrating strata such as oil, pitch, ben

tonite, and the like.

A further feature of my invention is the abilflected wave. A j

Other objects, ieaturesfand advantages of inventionmay appear .fromthe accompanying drawing, the subjoined detailed description, and

the appended claims.

In-Ithe drawing:

Figure 1 is a diagrammatic view of myappl.

r'atus, 1

Figure 2 isa longitudinal, sectional view'of the impact protective relay. 1 x c oi the recorder.

polarized relay. V I Figure isa longitudinal, sectional view of the dash pot control in the impact relay. Referring more particularly to the. drawing, the

I means for the amplifying tubes, to prevent-them Y ity to accurately measure the time interval from I the original shock, explosion or impact to the reformer Etc 8. spring contact arm 8. The spring contact arm 8 is adapted to contact either of the contacts 9 or-ifl, as will be further described.

The other end of the secondary coil of the transformert is connected to the main lead i l. which extends to the filaments of the tubes in the amplifier 2. The filaments in the various tubes are connected'to the motor generator 1; in the usual and well-known manner. I prefer that the amplifier 2 be or the resistance, impedance, coupled type, although I do not wish to limit myself to this particular type of amplifier since other hookups might be used.

The-contact 9-is connected to the grid of the relay tube l2, and the contact i0 is electrically connected to the grid of the first amplifying tube it; The primary coil of the polarized relay transformer it is electrically connected at one end to the motor generator-set l, and at the other end to the plate ofthe last amplifying tube lit. The

secondary coil of the transformer it is wired in series with the polarized relay l 6. The polarized relay I8 comprises an oscillating armature l1,

f which is pivotally mounted in the field of the .within the field of the magnet around the armafixed magnet It. The coil |9',,which is wound ture ll, is connected. in serieswith the secondary coil or the transformer N, as previously stated.

' the armature in moving from plus to minus (that numeral I indicates a motor generator set of the;

'usual-and well-known type, which is used when my, apparatus is transported from place to place,

although if a local source or electrical energy is available, the motor generator set can be dispensed with and the local source used in its stead.

The motor generator set I (or other source of energy) supplies the necessary electrical current to the amplifier and the impact protective relay 3.

A microphone 4 is-wired to one coilof the microphone transformer 5-. The usual battery Bis connected in series between the transformer coil and the microphone, all of which is a usual and well-known practice in the art. A lead I connests one end or the secondary coil or the trans- The armature I! alternately engages the spaced contacts 49, 20, and a battery 2| is connected in series with the contacts l9 and 20. Note that is, engaging the contacts I9 and 20) changes the polarity of the E. M. F. fed to the coil of the 'recorder. The polarity change is thus made the same in intensity. I

A lead 22 extends from a center tap on the bats tery 2| 'to one end of the coil 23 of the recording 'motor 26. A lead 25 extends from the other end ofthe coil 23 to a variable resistance 26, and .thence from the other end of this resistance to the armature II. By varying the resistance 26, it is possible to vary the amplitude of movement of the recording needle'or stylus, w ich will be subsequently described. The coil 23 is-mounted for oscillatory movement in the field of the fixed magnet 21. A spring 28 is -attached to the coil 23, and suspends this coil in the field of the magnet'2'I. The movement of current throu h this coil tends to. oscillate the coil in the field of themagnet. The amount of current flowing through the coil 23, therefore, determines the amplitude or throw of the coil in the held of the magnet 21, and the current flowing in this coil is therefore cont olled by the variable resistance 26.

this motor, vibrates in accordance with the re- An ink well 29 is pivotally mounted adjacent the magnet 21, and is connected to the coil 23 by a link 38. As the coil 23 oscillates, the ink well 29 will be partially rotated about a vertical axis. A stylus 3| extends from the ink well 29 and engages the tape 32. The tape 32 is drawn under the stylus 3I at a constant speed by a suitable motor 33, which drives the tape rollers 34. The tape 32 extends between these rollers, and is drawn over a table 35 at a constant and known speed. The stylus 3I thus draws a visual record on the tape 32, as briefly shown at 36. This recrd is an actual indication of the various sub-surface strata and bodies from which a sound wave is reflected. The vibration impact wave which vibrates the earth may be created on the surface or at various depths below the surface, as desired. The returning reflected waves are picked up by the microphone 4, are suitably amplified in the amplifier 2, are then controlled as to amplitude through the polarized relay, and are recorded through the recording motor 24 to the stylus 3 I.

The initial shock, which may be created by a charge of powder or any other suitable means, will usually have a very serious effect upon the amplifying tubes, as shocks of too great an intensity tend to paralyze the amplifier tubes, thereby rendering them inactive. It will overload this tube, causing it' to choke and, therefore, paralyzing its activity. To protect the amplifying tubes, I provide the impact protective relay 3, which consists of an electro-magnet 31, the core of which is adjacent to a pivotally mounted control arm 38. The spring arm 8 normally is caught in a recess in the arm 38, and is held in engagement with the contact 8. The coil 39 of the electro-magnet 31 is connected at one end to the plate of the relay tube I2, and at the other end to a bus 48 extending to the 90 volt tap from the motor generator I, and thence to the grid of the tube I5. When the first sound shock or vibration occurs, the arm 38 will be retracted, permitting the contact arm 8 to engage the contact ID. The contact I0 is electrically connected to the grid of the first amplifying tube I3.

To delay the movement of the arm 8 in engaging the contact H], I may provide a dash pot 4| either of the bellows or cylinder type, thus delaying the contact at I8 until the initial explosive sound shock has subsided. When the contact arm 8 engages I8, the amplifying of the return sound waves willproceed as will be evident from the diagram in Figure 1, and the previous description. Before each initial charge is set off, the arm 8 is hooked onto the control arm 38 by means of the spring-pressed plunger 42.

In operation, the microphone 4 is attached to a body, which will vibrate with the earth, such as an embedded metal stick, post or the like. The arm 8 is cooked to engage the control arm 38, and the spring 43 holds the control arm in engagement'with the arm 8. A charge is then set off suflicient to vibrate the earth. The arm 8 is then released through the energy created in the electro-magnet 31, the electro-magnet withdrawing the arm 38 from the arm 8. The returnwaves or echoes are then picked up by the micro- ;phone 4, and are amplified through the amplifier 2, and the'amplified waves are transmitted to the polarized relay I8 through the transformer The recording motor 24, or the coil 23 of ceived amplified waves, thus actuating the ink well 28 and the stylus 3|. In order that the stylus 3I may be kept within the confines of the tape 32, the amplitude of thestylus must be controlled, and this is effected through the variable resistance 26. When the proper amplitude has been determined, the resistance 26 is left in its set position. Thereafter, the amplitude of the needle 3I will be determined wholly by the energy of the return or reflected waves.

It will be evident that as soon as a run is completed, the record on the tape 32 will be available for interpretation by the operator. It maybe desirable to run several records Within short intervals of time; the various records can then be correlated, thus eliminating possible errors. The presence of oil, bituminous substances, bentonite, and the like, are determined by the character of the mark made on the tape 32 by the stylus 3|. Since the tape 32 is drawn under the stylus at a fixed and known speed, the depth of the various strata or deposits can be determined by measuring from the point of initial impact indicated by the stylus to the point determined by the oper-' ator, as that indicating the desired strata or deposit.

The recording circuit from the tube I2 to the coil 23 is as follows: The contact 9 is engaged, due to the fact that the switch arm 8 is held in raised position by the control arm 38. Current then passes through the lead I, thence through the contact 8 to the grid of the tube I2. The plate of the tube I2 then receives the impulse,

which is carried to the coil 39 of the magnet 31.

The current, after passing through the coil 39, traverses the lead 40, and thence to the grid of the tube I5. The plate of the tube I5 then receives the impulse, which is transmitted to the primary coil of the transformer I4. This transformer is electrically connected to the polarized relay I6, and the contacts I9, 28 of the relay are connected through the leads 22, 25 respectively, to the coil 23. Thus the initial shock of the explosion is recorded on the tape, and as soon as the tube I2 is energized, as previously described, the electro-magnet 31 operates causing the switch arm 8 to engage the contact III, thus throwing the tubes I3-I5 into the circuit, and thereafter, these last-named tubes operate the apparatus.

To provide satisfactory tripper action, the tube I2 is so biased as to carry a high plate current. Upon impact, that is, when the explosive charge is set off, there is a violent plate current surge, which causes the collapse or paralysis of the tube I2 for an instant. This affects the grid supply of the tube I5, causing it to operate the recorder. My experience leads me to assume that this action is not necessarily due to impedance or capacity coupling of any sort, but rather to the plate current surge. It is quite possible that the voltage divider of Fig. 1 plus the filtering condensers of the B supply play a considerable part in the results as outlined above.

However, the coil 39 does have an impedance reaction through the B circuit to the grid of th tube I5.

Having described my invention, I claim:

1. An apparatus for seismic prospecting comprising a microphone, an amplifier electrically connected to the microphone and adapted and arranged to amplify the sounds received by the microphone, a recording motor electrically connected to the amplifier, said recording motor including a movable coil, a stylus, means pivotally mounting said stylus, means connecting the stylus mount and the movable coil in the recording motor whereby movement of said coil is tape under the 'stylus at a regular and known speed, a polarized pflot relay having an armature coil, a transformer, one coil of said transformer being electrically connected to the armature coil, the other coilof said transformer being'electrically connected to the amplifier, a variableresistance, said variable resistance being electrically connected between the polarized relay and the coil of the recording motor, a battery having its midpoint connected to the coil of the recording motor,- and relay contacts providing electrical connection with either pole of the battery through said variable resistance, whereby movement of the recording motor coil is controlled.

prising a microphone, an amplifier electrically connected to the microphone, said amplifier being adapted and arranged to amplify the sounds received by the microphone, an output transformer, the primary coil of the output transformer being electrically connected to the amplifier, a polarized pilot relay, including a magnet, an armature pivotally mounted in the field of the magnet, a coil surrounding the armature, said coil being electrically connected to the secondary coil of the output transformer, a pair of spaced contacts, said contacts being alternately engageable by the armature, abattery, said battery being connected in series with said spaced contacts, a variable resistance, one end of the variable resistance being electrically connected to the armature, a recording motor including a fixed magnet, a coil movably mounted in the field of the fixed magnet, one end of. the last-named coil being electrically connected to said battery and the other end of said last-named coil being electricallyconnected to the variable resistance and thence to the armature of the pilot relay, a stylus, means pivotally mounting the stylus, means connecting the stylus mount and the coil in the recording motor, a tape, andmeans to pull said tape under the stylus at a regular and known speed;

3. An apparatus .for seismic prospecting comprising a microphone, an amplifier electrically connected to the microphone and adapted and arranged to amplify the vibrations received by the microphone, a recording motor, said ecord ing motor including a permanent magnet, a coil 15, 2. An apparatus for seismic prospecting commovably'mounted in the field of said magnet.

said coi1 being electrically connected to the amplifier, spring means mounting the coil into the field of the magnet, a stylus, means pivotally mounting the stylus, a link connecting the stylus mount and the coil, a tape and means to pull said tape under the stylus at a regular and known speed, a polarized pilot relay having an armature coil, a transformer, one coil of said transformer being electrically connected to the armature coil, the other coil of said transformerbeing electricallylconnected to the'amplifier, a variable resistance, said variable resistance, being electrically connected between the polarized relay and the coil of the recording motor, a battery having its midpoint connected to thecoil of the recording ,motor, and relay contacts providing electrical connection with either pole of the battery through said variable resistance, whereby movement of the recording motor toll is controlled.

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